1. Field of the Invention
The present invention relates to a micro-droplet generator, particularly to a micro-droplet generator which works by the piezoelectric effect, producing a well-defined flow of tiny droplets.
2. Description of Related Art
Currently available sprayers have two kinds, which work by direct pressure and by vibrations, generating pressure that disperses micro-particles. A common disadvantage of conventional sprayers is the need of large pressure when relatively large particles are generated, resulting in a large noise. For medical applications, spraying of relatively large particles is not required, but precise particle sizes are important. Therefore, sprayers working by vibration have recently been preferred for medical applications. Sprayers of this kind use ultrasound, generated by piezoelectric material, to produce micro-droplets. Shortcomings of these sprayers, however, are high power consumption, the need of a fan to drive micro-droplets into a given direction, a large volume, and non-uniform distribution of micro-particle sizes. Other sprayers which use piezoelectric material have spraying plates with holes of defined diameters to disperse micro-droplets, resulting in considerably reduced power consumption and well-defined micro-droplet sizes. Sprayers of this kind, disclosed in patent or sold on the market, are of two sub-kinds: Sprayers of the first sub-kind by direct vibrational pressure force micro-droplets through spraying plates, sprayers of the second sub-kind have vibrating spraying plates, causing micro-droplets to pass through. Sprayers of the first sub-kind have a higher power consumption than sprayers of the second sub-kind. The latter in some versions use planes that are tapped on, e.g., planes attached to capillary tubes transmitting liquid at ends thereof. These designs, however, have the following shortcomings:    1. Energy is easily dissipated.    2. Volume is large.    3. Manufacturing cost is high.    4. Tapped planes attached to capillaries allow only for small spraying angles.    5. Spraying is performed with limited effectiveness.